Legacy communications systems such as the Personal Handy-phone System (PHS) are configured to be simple and low cost. Differential demodulation has been adopted based on the technological constraints present at the time of designing these systems for baseband demodulation and therefore does not have the capability to combat inter-symbol-interference typically introduced by multi-path fading.
It is therefore desirable to provide a modernized baseband design compatible with or to retrofit these legacy systems. It is further desirable to employ advanced DSP algorithms and introduce adaptive equalization to realize coherent demodulation.